#include <stdlib.h>
#include "stack.h"

//TODO: grundlegende Stackfunktionen implementieren:
/*  * `push`: legt ein Element oben auf den Stack,
    * `pop`: entfernt das oberste Element,
    * `top`: liefert das oberste Element zurück,
    * `clearStack`: gibt den gesamten Speicher frei. */

// Pushes data as pointer onto the stack.
StackNode *push(StackNode *stack, void *data)
{
    if(stack && data){
      StackNode *t = (StackNode *)malloc(sizeof(StackNode));
      if(!t)
        {
        return NULL; //Speicherfehler
        }
      t->prev = stack;
      t->data = data;
      return t;
      }
    return NULL;
}

// Deletes the top element of the stack (latest added element) and releases its memory. (Pointer to data has to be
// freed by caller.)
StackNode *pop(StackNode *stack)
{

}

// Returns the data of the top element.
void *top(StackNode *stack)
{

}

// Clears stack and releases all memory.
void clearStack(StackNode *stack)
{

}